Rheology is the study of flow and deformation of materials. An understanding of rheology can lead to insights that are critical in order to control and optimize various industrial processes (such as pumping, extruding, etc.) and consumer processes (dispensing a shampoo, rubbing a skin cream, etc.).
Rheology by its very nature is a complex science. Accurate insights can generally only be obtained through properly set up experiments in which the sample is correctly loaded, the correct geometry is used and the actual rheometry test and test parameters are representative of the process for which the insight is required. This is inherently difficult, as in addition to an understanding of the process it requires an understanding of the material type (gel, low viscosity solution, melt, etc.) and its response to loading conditions and geometries (thixotropy, slippage, etc.).
In terms of accurately setting up the test to be representative of the process (for example pumping, spreading, etc.) an understanding is required of whether the process is shear, extension or tension, whether it is stress or strain controlled, what are the relevant shear stresses or shear rates, and so forth.
The ability to take this understanding of material and processes and accurately set up the relevant rheological test requires input from people highly skilled in experimental rheology. Conversely, the lack of properly set up and executed rheological experiments can lead to inaccurate insights being generated and an inefficient use of resources if such personnel are not available.